Economists surveyed by Reuters expect the European Central Bank to cut its main refinancing rate to 0.1 percent and launch a package of other stimulus measures at the conclusion of its policy review at 7:45 pm SIN/HK.

"We need to be cognizant that traders are looking out for a lowering of the rates 'corridor' (i.e. a cut to the lending, refinancing and deposit rate), however the ECB's inflation expectations are also in focus and likely to be lowered, with Draghi's press conference focusing on more unconventional policy easing. The conference is where we look out for a new capital injection into banks or measures to expand excess liquidity in the region," said Chris Weston, chief market strategist at IG.

Michael Woolfolk, Global Markets Division MD & Senior Currency Strategist, Bank of New York Mellon, explains why the central bank may not unleash all its policy options at one go.

Nikkei flat

Japanese shares managed to end at a near three-month high, extending gains into a fourth straight session. Profit-taking and a stronger currency capped gains however, as the yen retreated from Wednesday's one-month low of 102.79 per dollar.

Australia's benchmark index fell to a new two-week low, extending losses into a third session, after data showed the economy posted a trade deficit of A$122 million in April, compared to forecasts for a surplus of $A300 million.

South Korea's benchmark index ended at a three-week low as investors sold off shares before Friday's Memorial Day holiday. Markets were also shut Wednesday for regional elections. For the week, the Kospi index was flat.